BR and Auxin Have Shared Genomic Effects

<div><p>(A) Venn diagram showing relative proportion of BR- and auxin-responsive genes and the degree of overlap.</p> <p>(B) Functional categories of BR–auxin shared genes reveal a potential growth signature.</p> <p>(C and D) Effects of auxin on BR-regulated gene expression. Transcripts which show elevated levels are shown in orange, those with decreased levels are shown in blue, and those transcripts whose levels are not changed are shown in yellow. (C) Relative ratios were derived from the following comparisons (from left to right): BR versus mock treatment (WT plants; B), auxin versus mock treatment (WT plants; A), and <i>yucca</i> versus WT (Y). The three columns to the left are BR-upregulated genes and the three columns to the right are BR-downregulated genes. Among the BR-upregulated genes, there are a large number that are also induced by auxin treatment or in a <i>yucca</i> background. Few BR-repressed genes are repressed by auxin. nc, no change. (D) Effect of BR treatment in <i>yucca</i> background. Relative ratios represent BR versus mock treatment in WT plants (WT) or in <i>yucca</i> mutants (YB). Approximately two-thirds of BR-regulated genes were not affected by BR treatment of <i>yucca</i> plants.</p> <p>(E) Quantitative PCR shows that shared target genes are synergistically induced when treated with both auxin and BRs. At5g64770 encodes a protein with unknown function. At1g18400 encodes BEE1, a bHLH-containing protein known to be required for the BR response (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020258#pbio-0020258-Friedrichsen1" target="_blank">Friedrichsen et al. 2002</a>). At1g10550 and At4g30290 are putative endoxyloglucan transferases. Asterisks indicate response under an additive model.</p>